A production method of fluorinated compounds, for producing a compound represented by formula (3) in a fluorine-based solution in a flow of fluorine gas after reaction of at least one type of compounds represented by formula (1) and at least one type of compounds represented by formula (2). Similarly, fluorinated compounds represented by formula (4) prepared by the fluorination of compounds obtained by the reaction of formula (1) and formula (2)′. The fluorinated polymers obtained by the polymerizations of formula (3) and (4) compounds are useful as an optical or electrical materials. wherein R1, R2, R3, R4, Rff1, Rff2, Rff3, Rff4, X, Y, Z, and n are defined in the specification respectively.